1. Software Engineering
Unit- 1
Engineered for Tomorrow
CSE, MVJCE

2. Subject Name: Software Engineering Subject Code: 10IS51
Prepared By: Alpana, Hymavathi
Department : CSE
Date : 30/8/2014
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3. 1.1. Professional Software development
UNIT 1-Introduction
1.1. Professional Software development
1.2. Software engineering ethics
1.3. Case Studies
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4. 1.1.Professional Software development
Professional Software, intended for use by some one apart from its developer, is usually developed by teams rather than individuals.
Software engineering is intended to support professional software development rather than individual programming.
The Professional software development comprises of number of separate programs and configuration files that are used to set up these programs.
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5. Frequently asked questions on software engineering
Computer programs and associated documentation. Software products may be developed for a particular customer or may be developed for a general market.
Attributes of good software
Good software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable.
Software engineering
Software engineering is an engineering discipline that is concerned with all aspects of software production.
Software engineering activities
Software specification, software development, software validation and software evolution.
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6. Frequently asked questions on software engineering
Difference between software engineering and computer science
Computer science focuses on theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software.
Difference between software engineering and system engineering
System engineering is concerned with all aspects of computer-based systems development including hardware, software and process engineering. Software engineering is part of this more general process.
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7. Frequently asked questions on software engineering
The key challenges facing software engineering
Coping with increasing diversity, demands for reduced delivery times and developing trustworthy software.
The costs of software engineering.
Roughly 60% of software costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs.
The best software engineering techniques and methods
While all software projects have to be professionally managed and developed, different techniques are appropriate for different types of system. For example, games should always be developed using a series of prototypes whereas safety critical control systems require a complete and analyzable specification to be developed. You can’t, therefore, say that one method is better than another.
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8. Frequently asked questions on software engineering
What differences has the web made to software engineering.
The web has led to the availability of software services and the possibility of developing highly distributed service-based systems. Web-based systems development has led to important advances in programming languages and software reuse.
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9. Engineering discipline:
Software engineering
Software engineering is an engineering discipline that is concerned with all aspects of software production from the early stages of system specification through to maintaining the system after it has gone into use.
Engineering discipline:
Using appropriate theories and methods to solve problems bearing in mind organizational and financial constraints.
All aspects of software production:
Not just technical process of development. Also project management and the development of tools, methods etc. to support software production.
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10. 1.2 Essential attributes of good software
Maintainability
Software should be written in such a way so that it can evolve to meet the changing needs of customers. This is a critical attribute because software change is an inevitable requirement of a changing business environment.
Dependability and security
Software dependability includes a range of characteristics including reliability, security and safety. Dependable software should not cause physical or economic damage in the event of system failure. Malicious users should not be able to access or damage the system.
Efficiency
Software should not make wasteful use of system resources such as memory and processor cycles. Efficiency therefore includes responsiveness, processing time, memory utilisation, etc.
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11. 1.2 Essential attributes of good software
Acceptability
Software must be acceptable to the type of users for which it is designed. This means that it must be understandable, usable and compatible with other systems that they use.
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12. 1.Stand-alone applications
1.1.2.Software engineering diversity
There are many different types of software system and there is no universal set of software techniques that is applicable to all of these.
The software engineering methods and tools used depend on the type of application being developed, the requirements of the customer and the background of the development team.
1.Stand-alone applications
These are application systems that run on a local computer, such as a
PC.
2.Interactive transaction-based applications
Applications that execute on a remote computer and are accessed by users from their own PCs or terminals.
3.Embedded control systems: These are software control systems that control and manage hardware devices.
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13. 4.Batch processing systems- These are business systems that are designed
to process data in large batches.
Entertainment systems- These are systems that are primarily for personal use and which are intended to entertain the user.
Systems for modelling and simulation-These are systems that are developed by scientists and engineers to model physical processes or situations which include many, separate ,interacting objects.
Data collection systems-These are systems that collect data from their environment using a set of sensors and send that data to other systems for processing.
Systems of systems – These are systems that are composed a number of other software systems like spread sheet programs.
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14. Users do not buy software buy pay according to use.
1.1.3 Software engineering and the Web
The Web is now a platform for running application and organizations are increasingly developing web-based systems rather than local systems.
Web services allow application functionality to be accessed over the web.
Cloud computing is an approach to the provision of computer services where applications run remotely on the ‘cloud’.
Users do not buy software buy pay according to use.
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15. 1.2 Software engineering ethics
Software engineering involves wider responsibilities than simply the application of technical skills.
Software engineers must behave in an honest and ethically responsible way if they are to be respected as professionals.
Ethical behaviour is more than simply upholding the law but involves following a set of principles that are morally correct.
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16. Issues of Professional Responsibility: Confidentiality
Engineers should normally respect the confidentiality of their employers or clients irrespective of whether or not a formal confidentiality agreement has been signed.
Competence
Engineers should not misrepresent their level of competence. They should not knowingly accept work which is out with their competence.
Intellectual property rights
Engineers should be aware of local laws governing the use of intellectual property such as patents, copyright, etc.
Computer misuse -Software engineers should not use their technical skills to misuse other people’s computers.
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17. Software Engineering Code of Ethics and Professional Practice
ACM/IEEE-CS Joint Task Force on Software Engineering Ethics and Professional Practices
PREAMBLE
The short version of the code summarizes aspirations at a high level of the abstraction; the clauses that are included in the full version give examples and details of how these aspirations change the way we act as software engineering professionals. Without the aspirations, the details can become legalistic and tedious; without the details, the aspirations can become high sounding but empty; together, the aspirations and the details form a cohesive code.
Software engineers shall commit themselves to making the analysis, specification, design, development, testing and maintenance of software a beneficial and respected profession. In accordance with their commitment to the health, safety and welfare of the public, software engineers shall adhere to the following Eight Principles:
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18. The ACM/IEEE Code of Ethics(IEEE/ACM 1999)
1. PUBLIC - Software engineers shall act consistently with the public interest.
2. CLIENT AND EMPLOYER - Software engineers shall act in a manner that is in their best interest.
3. PRODUCT - Software engineers shall ensure that their products and related modifications meet the highest professional standards possible.
4. JUDGEMENT - Software engineers shall maintain integrity and independence in their professional judgment.
5. MANAGEMENT - Software engineering managers and leaders shall subscribe to and promote an ethical approach.
6. PROFESSION - Software engineers shall advance the integrity and reputation of the profession .
7. COLLEAGUES - Software engineers shall be fair to and supportive of their colleagues.
8. SELF - Software engineers shall participate in lifelong learning regarding
. Practices..
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19. 1.3 Case studies
The three types of systems used for case studies are as follows:
An embedded system-An embedded system in an insulin pump used by diabetics to maintain blood glucose control.
An information system-A system named mental health care patient management system(MHC-PMS) used to maintain records of people receiving care for mental health problems.
3. A sensor based data collection system-A data collection system named wilderness weather station that collects data about weather conditions in remote areas.
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20. Calculation based on the rate of change of blood sugar levels.
1.3.1 An insulin pump control system
Collects data from a blood sugar sensor and calculates the amount of insulin required to be injected.
Calculation based on the rate of change of blood sugar levels.
Sends signals to a micro-pump to deliver the correct dose of insulin.
Safety-critical system as low blood sugars can lead to brain malfunctioning, coma and death; high-blood sugar levels have long-term consequences such as eye and kidney damage.
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21. Figure 1.4 Insulin pump hardware
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22. Figure 1.5 Activity model of the insulin pump
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23. 1.3.2 A patient information system for mental health care
A patient information system to support mental health care is a medical information system that maintains information about patients suffering from mental health problems and the treatments that they have received.
Most mental health patients do not require dedicated hospital treatment but need to attend specialist clinics regularly where they can meet a doctor who has detailed knowledge of their problems.
To make it easier for patients to attend, these clinics are not just run in hospitals. They may also be held in local medical practices or community centres.
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24. Figure 1.6 The organization of the MHC-PMS
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25. 1.3.3 A wilderness weather station
The government of a country with large areas of wilderness decides to deploy several hundred weather stations in remote areas.
Weather stations collect data from a set of instruments that measure temperature and pressure, sunshine, rainfall, wind speed and wind direction.
The weather station includes a number of instruments that measure weather parameters such as the wind speed and direction, the ground and air temperatures, the barometric pressure and the rainfall over a 24-hour period. Each of these instruments is controlled by a software system that takes parameter readings periodically and manages the data collected from the instruments.
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26. Figure 1.7 The weather station’s environment
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